THE ROTATION VELOCITY-DENSITY RELATION

We have assembled 21-cm linewidths for 376 of the 732 galaxies in a ma gnitude-limited redshift survey of the Perseus-Pisces region. We analy ze a distance limited subset of 271 galaxies (131 widths) to examine t he relationship between linewidth and local density. The sample indica tes that galaxies with linewidths greater than or similar to 480 km/s are absent from regions where the galaxy density is less than or simil ar to 0.03 galaxies Mpc(-3) (M(B(0)) < -18.3). This effect is in the d irection predicted by standard CDM models. Galaxies with linewidths le ss than or similar to 480 km/s appear throughout the sample. The obser vational constraints could be substantially improved with a larger sam ple, IR photometry, and more uniform 21-cm data. (C) 1996 American Ast ronomical Society.